Control device for draft regulators



June 1?, 1947. c. H. MORROW CONTROL DEVICE FOR DRAFT REGULATORS FiledJan. 4, 1945' 2, Sheets-Sheet 1 FTc-b. L

INVENTORQ Cumanca HMonRow man/2m.

' June. 17, 1947. c. H. MORROW 2,422,496

CONTROL DEVICE FOR DRAFT REGULATORS Filed Jan. 4, 1945 2 Sheets-Sheet 2Face. 5. INVENTOR.

CLnRsNcE, H. Mo'maow FTTOtMaEY Patented June 17,1947

UNITED STATES OFFICE CONTROL DEVICE FOR DRAFT REGULATORS ApplicationJanuary 4, 1945, Serial No. 571,239

3 Claims.

This invention relates to control or operating mechanism for a furnacedraft stabilizing damper. It is an improvement upon the constructionshown, described and claimed in Patent No. 2,381,437, for Control meansfor draft regulators, granted August '7, 1945, to Morris W. Crew andGeorge A. Short, to which referenc may be had for more completeunderstanding of certain of the features, if not completely described orshown here,

The control mechanism of said patent includes an operating membermovable back and forth between two positions and driven in one directionby an electric motor of such form as to permit it to stall withoutinjury, and in the opposite direction by suitable power means, such as aspring, said operating member being connected to the damper bydisconnectible parts, all of the said parts being constructed andarranged so that with the mechanism in stand-by position and the motordeenergized, upon a thermostatic call for more heat, the motor isenergized and drives the operating member in one direction to suddenlyrelease the damper for normal stabilizing action during the period whilethe burner operates. When the demand for more or additional heat issatisfied, the motor circuit is deenergized and the operating memberthen is moved in the opposite direction by the power spring or otherpower source connected thereto, to slowly return the parts to theiroriginal position. Such mechanism includes speed reducing gearing drivenby the motor and certain latch and holding devices.

The present invention has for its object to improve the mechanism ofsaid patent by the inclusion in the operating connections between themotor and operating member of a floating coiled spring clutch soarranged that driving relation from the motor to the operating member,or vice versa, is permitted in one direction only, as will more fullyappear hereinafter, for the purpose of distributing the wear on thespeed reducing gears uniformly over their entire periphery, instead oflimiting it to only a part of the teeth; which prevents gear clash andthe impact of the momentum of the motor armature upon the gear teethwhen the parts come to rest, with possible damage of the gears, asheretofore; and which avoids any possibility of bounce or return of theparts by reverse motion with consequent inaccuracy and possible faultyoperation of the latching and disconnectible operating parts.

Further objects of the invention in part are obvious and in part willappear more in detail hereinafter.

Cal

In the drawings, which represent one suitable embodiment of theinvention, Fig. 1 is a longitudinal sectional elevation through afurnace damper provided with my improved control, the front wall of thecontrol casing being omitted to expose interior parts;

Fig. 2 is a similar view, showing the parts in another position;

Fig. 3 is a detail sectional view illustrating the speed reducing gear;

Fig. 4 is a sectional elevation on a larger scale, on the lin d, Figs. 1and 3, showing the oneway clutch;

Fig. 5 is a detail end view from the right in Fig. 4; and

Fig. 6 is a sectional plan view on the line 6-6, Fig. 5.

Complete description of all of the parts of the mechanism isunnecessary, since reference may be had to said patent where that isdesirable or necessary. It will suffice for this application to refer tomany of the parts in a general way, as follows:

l0 indicates a damper mounted for pivoting movement in a sleeve-likeframe or housing ll adapted for connection to a pipe leadingfrom afurnace to the stack for controlling the flow of the check draft. Fig. 2represents the stand-by position, in which the damper is held wide open,while Fig. 1 illustrates the position the parts assume upon a call forheat or more heat, the damper being free for normal stabilizing action.

Movement of the damper to one or the other of its positions is producedby an operating member l2, movable back and forth between two positions,as by reverse swinging motion about a pivot. The operating member shown,as in said patent, is a two-armed device, one arm of which, I3, isconnected by disconnectible connections, indicated generally at M, to alink l5 connected to the damper. The disconnectible connectionscooperate with a pivoted latch It. The other arm I! of the operatingmember is connected to a suitable source of power, such as the tensionspring IS.

The spring it always tends to move member l2 in the counterclockwisedirection, Fig, 1. It may also be driven in the clockwise direction byan electric motor, marked generally M, which drives the shaft 26, aroundthe axis of which member I2 turns, by means of speed reducing gearingshown more or less diagrammatically in Fig. 3, and including a series oflarge gears 2| and small pinions 22, the drive being from the motorshaft 23 to.

the first small pinion, then to a large gear, and so on to the finalslow speed shaft 20.

With the arrangement described, as in the patent before referred to, theparts lie in the positions shown in Fig. 2 upon a stand-by. The electricmotor is deenergized and the parts are held in the stand-by position bythe tension of spring I8 and the engagement of pivot 24, about whichlink swings, with the end of the slot 25 in said link.

Upon a call for heat or more heat by the thermostat (not shown) saidthermostat closes the motor circuit and the motor immediately begins torotate in a direction to turn member I 2 in the clockwise direction.Practically immediately, the disconnectible connections separate and thedamper is released and. moves promptly to its position shown in Fig. 1,for normal stabilizing action. finally the second arm of member l2, towhich spring [8 is secured, engages the stop 26, with the parts in theposition shown in Fig. 1. There they remain until the call for heat issatisfied, whereupon the motor circuit is opened. The motor, of course,is of the ordinary clock motor type, capable of being stalled withoutinjury, as described in said patent.

When the motor circuit is opened spring [8 begins to turn member I2 inthe opposite direction, also driving the rotor of the electric motorreversely through the speed reducing gearing, the latter serving toretard motion of member I2 and delay the completion of motion of thedamper to the stand-by position shown in Fig. 2.

According to the present invention, for purposes and advantages to belater referred to I introduce into the dliVil'lg connections between theelectric motor and operating member 2 a one-way or overrunning clutchdevice or mechanism, of special form, and so arranged, that drivingeffect may be produced from the speed reducing gearing to member l2, orreversely from member l2 to the The motor continues to rotate until jspeed reducing gearing, but in each case only in one direction.

The mechanism is relatively small, space being at a premium in andaround the space at the hub of lever l2. Accordingly I provide a verycompact and improved spring clutch which may be made and operativelyassembled with the other parts by simple operations and at low cost.

The drawings show for the purpose one suitable form of spring clutchillustrated in detail in Figs. 4, 5 and 6. As illustrated the end of theslow motion shaft 2% is left plain, except for a small diameter crosshole 39 to receive a securing cotter pin 3 I. Around the shaft issleeved a coiled clutch spring 32 having its inner end plain, at 33, andits outer end bent tangentially to form an operating arm 34.

Spring 32 is housed or enclosed in the cavity 35 of a sleeve-like hub 36permanently fastened to and forming the hub of lever [2, the outer endof said hub being provided with a slot 37 to receive the operating arm36. Cavity 35 at its inner end is slightly enlarged, at 38, to house theplain inner end of the spring clutch and avoid any sticking effect suchas might be caused by a rough end of the spring riding on metal of thehub.

The turns of the coil spring are fairly close together and said coil hassuch internal diameter that it is a snug fit upon shaft 20. In otherwords all of its turns at all times are in actual contact with a lightfrictional drag upon the shaft surface. The direction of twist, right orleft, is such that When the hub is held stationary, as in Fig. 5,

4 clockwise rotation of the slow speed shaft 20 tends to close or windthe coils more tightly about the shaft, while shaft rotation in theopposite direction tends to open up the coils and free them from theshaft. Thus, the spring serves as a one-way driving clutch, permittingdriving effect from shaft 28 to the hub, or vice versa, but in each casein one direction only.

With the construction described, assuming the parts in the stand-byposition Fig. 2, and that the thermostat has called for heat or moreheat and thus has closed the motor circuit, the motor begins to turn inthe clockwise direction Fig. 1. Practically immediately thedisconnectible parts are disconnected, as in said patent, and the damperpromptly moves to the position shown in Fig. 1, for normal stabilizingaction. The motor continues to operate, turning shaft zfi'and drivinghub 36 through the spring clutch in the clockwise direction Fig. 5, andturning member 12 until it engages the stop 26. Thereupon movement ofmember [2 stops, and through the clutch fully prevents further advanceor rotation of the motor rotor and reducing gear. The parts are held inthis position, with the motor stalled, so long as the motor isenergized.

When the call for heat is satisfied, the thermo-,- stat opens the motorcircuit, as before described, and the spring 18 becomes the operatingpower source, exertin its effect through member l2 upon the hub 36,driving it in the counterclockwise direction Fig. 5 and through theclutch 7 spring also turning shaft 20, the reducing gearing, and themotor rotor in the reverse direction from before. This operationcontinues until finallythe parts reach the position shown in Fig. 2,with the pin 24 at the end of the slot 25 and forming a positive stopfor motion of member l2. However, the one-way clutch now permits theshaft 20, speed reducing gearing and the motor rotor to continue torotate until the force and tendency to move have been expended infriction. The parts are then ready for the next cycle of operations.

The mechanism avoids. any possible rebound effect as the parts reach thestand-by position of Fig. 2. Heretofore, when the shaft 28' has" beenpositively connected to member I2, so that the two parts always rotatetogether, when the, parts reach the stand-by position,-driven by theforce of spring 8, at the moment of impact of the pivot pin 24 with theend of the slot 25, the heavy force of the rotating motor armaturecauses it to rebound, as it were, so, that in actual practice it mayrotate reverselyv as much as 10 or 15 revolutions. has been sufiicientto unlatch the disconnectible parts and permit false operation or motionofthe ing in the hub and the provision of the cross slot for itsintroduction into the device. v v

The construction described is simple, durable, effective. and not liableto get out of order, and may be applied both to new control devices-cor;as replacement parts for those already, in use-.

This rebound effect sometimes Further advantages of the invention willbe apparent to those skilled in the art.

What I claim is:

1. Apparatus of the character described, comprising an electric motor,speed reducing gearing driven by the motor and including a slow runningshaft member, an operating device having a hub member surrounding theshaft memher, power means connected to the operating device topositively turn it about the shaft axis, and a coil spring surroundingand closely fitting the shaft, one end of said spring being free and theother end being connected to one of said members, said spring serving asa one-way clutch between said members permitting drive through saidspring of said operating device by said motor in one direction only orof the motor by said operating device in the opposite direction only.

2. Furnace damper control mechanism of the character described,comprising, in combination, a damper, an operating device movable backand forth and having a disconnectible connection to said damper, anelectric motor, speed reducing gearing driven thereby and including aslow running shaft, and a coil spring surrounding and closely fittingsaid shaft, one end of said spring being free and the other end beingfastened to said operating device and power means efiective directlyupon said operating device and tending to move it reversely to itsmovement by the motor, said spring serving as a one-way clutch forestablishing driving connection through it'between the motor andoperating device.

6 V a 3. Control means for a furnace draft stabilizing damper,comprising an electric motor adapted while energized to be stalledwithout injury thereto, means operatively connecting said motor anddamper and having stand-by and damper release positions, said connectingmeans including speed reducing gearing connected to the motor rotor andincluding a slow running shaft, an operating device connected to thedamper and movable back and forth and having a hollow hub surroundingsaid shaft, power means effective upon said device and tending to moveit reversely to its movement by the motor, and a coiled springsurrounding the shaft and housed within the hollow hub and having oneend connected to said hub and the other end free, said spring serving asa one-way clutch between said reduction gearing and operating device topermit drive by either to the other in one direction only.

CLARENCE H. MORROW.

REFERENCES CITED 9 The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,021,413 Gille Nov. 19, 19352,381,437 Crew et a1 Aug. 7, 1945 2,169,168 Shipley Aug. 8, 1939

